A portable, inexpensive EEG/Sleep Recorder with no moving parts that can be used in patients' homes and hospital rooms will be designed and validated. Phase I research will focus on software necessary for data compression and "intelligent" monitoring of input signals to assure the quality of data collected with unattended operation. This technology will address the need of the growing field of sleep medicine to diagnose sleep disorders with greater efficiency and less expense. The portable sleep monitor will have no moving parts and will rely on random access memory for digitized data storage. The microprocessor-based device will be programmed to evaluate signals from transducers and to accept data only from the best of redundant sets. This strategy will increase the useful data yield of unattended operation. In addition, data compression techniques will reduce the amount of memory and battery power necessary to store 8 hours of polysomnographic data. This technology can also be applied to psychophysiological monitoring of circadian rhythms and extended performance, to long-term evaluation of breathing disorders, and to studies of worker health and performance in critical industries.